There are generally three types of shaving creams each having their own distinct properties: lathering; brushless or non-lathering; and post-foaming gel, or gel foam.
Lathering shaving creams are generally concentrated dispersions of alkali metal soaps in glycerol and water. The lathering effect exhibited by these shaving creams results from mixing stearic acid with a coconut oil fatty acid in a ratio of approximately 1 part to 3 parts. These shaving creams normally contain between about 30 and 50% soap and either potassium hydroxide, sodium hydroxide, or a combination of the two to saponify the fatty acids. As with other types of shaving creams, the formulation of a lathering shaving cream may include lubricants, fragrances, preservatives, foam stabilizers, humectants and the like.
Brushless, or non-lathering shaving creams are basically oil-water emulsions. These shaving creams have a lower pH than conventional lathering shaving creams and therefore, typically cause less irritation during and after shaving. Lower pH results from the absence of potassium hydroxide or sodium hydroxide. Lubricants, fragrances preservatives, humectants and other materials commonly used in a shaving cream mixture can also be present in this type of shaving cream.
The third type of shaving cream is the post-foaming gel, or gel-foam shaving cream. This is basically an aqueous dispersion. With this type of shaving cream, lather is typically formed in situ on the surface of the skin. The lathering effect is believed to result from the vaporization of low-boiling point aliphatic hydrocarbons.
Acne vulgaris is a common dermatological condition which affects a large portion of the population. The specific cause of this condition is still unknown. However, there is general agreement that the following can contribute to acne vulgaris: 1) an individual's genetic predisposition to acne; 2) the size of an individual's sebaceous gland, (see Cunliffe et al., The Acne: Clinical Features, Pathogensis and Treatment, 62, 66-67 (1975)); 3) the type and quantity of bacteria within the hair follicle, (see Marples et al., "Control of Free Fatty Acid in Human Surface Lipids . . . " 56 J. Investigative Dermatology 127-31 (1971)); 4) the androgenic stimulation of sebum, (see Shalita, "Acne Vulgaris Current Concepts in Pathogenesis Treatment International", 15 J. of Dermatology 182-87 (1976)); and 5) alterations to the keratinization process, (see Holms et al., "Philosebaceous Duct Obstruction in Acne", 37 British J. of Dermatology 327-33)).
Acne typically results in the formation of papules, pustules, or cysts which are often contaminated with bacteria. Such a condition is at best unsightly and at worst unhealthy, and as such, an effective treatment has been sought for many years.
Benzoyl peroxide, (C.sub.6 H.sub.5 CO).sub.2 O.sub.2, is a colorless, odorless, tasteless, crystalline solid which is generally stable at room temperature. Benzoyl peroxide has been first considered for the treatment of acne vulgaris since at least 1934. Vehicles used in the topical application of benzoyl peroxide include creams, lotions and gels. For example, U.S. Pat. No. 4,778,674 discloses a dry aerosol foam containing benzoyl peroxide for use in the treatment of acne vulgaris. However, the prior art methods and compositions have not been very successful in treating acne, either because of the compositions employed, the various methods of application, both, or for some other reasons.
In addition to acne, other serious skin conditions are pseudofolliculitis barbae, pseudofolliculitis of the beard, or pseudofolliculitis capitae, all more commonly known as "razor bumps." These conditions generally result from ingrown hairs. They typically occur on the human neck, jowl and chin, and are characterized by erythematous lesions, firm papules, pustules, or cysts which contain buried hairs. While these condition afflict many, it is particularly troublesome for those with curvy or curly hair. Curvy or curly hair, upon growing out of the hair follicle curves back in an arch, and penetrates the skin. This results in an inflammatory reaction which ultimately leads to the development of "razor bumps."
Past remedies for treating "razor bumps" included the use of depilatories, such as barium sulfide powder or calcium thioglycollate. However, it has been suggested that topical application of antibacterial agents such as tetracycline or petrolatum resulted in insignificant long-term effects, and therefore would be ineffective if used as a depilatory.
Though a depilatory has been used with some success in treating "razor bumps," such treatment can only be used on an infrequent basis by most people. Depilatories can result in skin irritation and generally should only be administered no sooner than every three days. This application schedule, however, will not alleviate the irritation in most people. Furthermore, even if such a schedule could be tolerated, it could not be used to treat pseudofolliculitis barbae. The growth of the beard during the period of time between depilatories would result in the person having a very unkempt appearance.
Other methods of treating pseudofolliculitis barbae have been attempted. For example, U.S. Pat. No. 4,228,163 discloses use of a synergistic combination of benzoyl peroxide and chlorohydroxyquinoline.
As a result of these unsightly and unhealthy conditions which afflict a large portion of today's society, it would be highly desirable to develop a composition which would effectively treat and control both acne vulgaris and pseudofolliculitis barbae. It would also be highly desirable that such composition be cosmetically pleasant, commercially acceptable, easy to use, easy to apply and have the ability to be used on a daily basis.
Accordingly, it is an object of this present invention to provide a novel and unique brushless or gel-foam shaving cream composition which is both physically and chemically stable when admixed with benzoyl peroxide in quantities which are therapeutically effective for the treatment of acne vulgaris or pseudofolliculitis barbae.
It would also be highly desirable to produce such a composition in a manner which would not degrade due to the presence of benzoyl peroxide, and further would not result in deterioration of the shaving cream system.
It would also be highly desirable to produce such a composition that would be easy to apply and non-gritty.
A further object of the present invention is to provide a new and improved method of preparing brushless or gel-foam shaving cream compositions which can be used for the treatment of acne vulgaris and pseudofolliculitis barbae.
A still further object of this invention is to provide an improved method for applying compositions which would be effective in the treatment of acne vulgaris and pseudofolliculitis.
These and still further objects shall become readily apparent following the detailed description of the present invention.